Introduction 

Heart failure in children is one of the most challenging areas in paediatric cardiology. Endocardial Fibroelastosis (EFE) is a rare, severe heart condition often seen in infants. It is characterised by abnormal thickening of the inner lining of the heart (endocardium) by elastic fibres and tissues, leading to unexplained heart failure. The cause is unknown but researchers speculate it involves a genetic mutation. Because of its rarity, only a few studies have been conducted to explore this condition. If all treatment options fail, heart transplantation is the only solution to EFE. 

Endocardial fibroelastosis: Background

Etiology 

EFE is categorised as primary or secondary. Primary EFE occurs when there is no underlying condition or cause, such as a genetic condition, to explain the thickening of the heart lining. Secondary EFE develops in association with another underlying condition, such as congenital heart disease including aortic stenosis or atresia, coarctation of the aorta, and hypoplastic left heart syndrome, viral infections, or genetic disorders. 

Pathophysiology 

The main problem in EFE is diffuse thickening of the endocardium, the muscular lining of the heart chambers. This thickening is caused by excess connective tissues, such ascollagen and elastic fibres, and this leads to heart failure. Normally, the heart contracts and relaxes to pump and receive blood from the entire body, but when the ventricular wall of the heart is thickened, it makes it stiff and less able to relax. A stiff ventricle can’t fill with enough blood, so less blood is pumped to the body. Over time, not only does the relaxation (filling) worsen, but contraction (pumping) also starts to weaken.

Symptoms 

Common clinical symptoms observed in infants include: 

• Feeding difficulty 
• Breathlessness
• Excessive sweating
• Respiratory distress
• Cough 
• Cyanosis - blue or grey skin or lips due to lack of oxygen in the blood 
• Swelling of the lower limbs

The most common symptom, which is not as apparent as the ones above, is heart failure following respiratory distress.¹ 

Medical management prior to transplant

An infant with heart failure is first assessed by healthcare practitioners before prescribing any medication or treatment.² Based on the tests, imaging, and function of different organs, an appropriate treatment plan is given. 

Diuretics

Diuretics, also called ‘water pills’, are usually the first line of medication given to children with heart failure. They help get rid of excess salt and water in the body by increasing urine frequency. This reduces fluid buildup in the lungs (pulmonary congestion) and in the rest of the body (swelling in the legs, belly, or other areas). The most common type used is called a loop diuretic, because it works effectively and quickly. 

Digoxin

One of the oldest and commonly used drugs to treat heart failure in infants, despite a lack of evidence. It is used to help the heart pump more effectively and maintain a steadier rhythm, reducing cardiac workload. Digoxin is not considered safe in premature babies, those with renal failure and those with acute myocarditis. 

Angiotensin-Converting Enzyme (ACE) inhibitors and Angiotensin II Receptor Blockers (ARBs)

ACE and ARBs are classes of medication that lower blood pressure, while also treating heart and kidney problems. They relax blood vessels and lower the resistance the heart has to pump against. In children with cardiac failure, the ACEIs which have been most studied are captopril and enalapril.^3,4 Children on ACE should have their kidney function and blood pressure monitored. 

Beta-blockers

In some cases, beta blockers are given. These medications slow the heart rate and help protect the heart muscle from stress hormones. Long-term use can lead to some problems, so doctors prescribe them only when necessary. They are proven to help adults with heart failure, but more research is needed to know how well they work in children. 

Limitations 

Even with the best use of these medications, children continue to get worse. This is because endocardial fibroelastosis causes fibrosis (scarring and stiffening) of the heart muscle. Once scar tissue forms, the heart cannot relax or contract normally. Medications can ease the symptoms and slow progression, but they cannot reverse these changes. That’s why children with advanced heart failure may eventually need more intense treatments, such as mechanical support or a heart transplant. 

Indications for heart transplant in EFE

A heart transplant is needed when the condition becomes severe and does not respond to any medication. This is called end-stage heart failure. It is needed in cases such as: 

• Severe symptoms (breathing difficulty, extreme tiredness, swelling) despite maximal medical therapy
• Heart pumping is inefficient (low ejection fraction) that limits normal activities
• Dangerous heart rhythms (ventricular arrhythmias)
• Chest pain 
• Severe heart injury or blocked arteries that cannot be fixed with surgery or stents
• Congenital heart defects (heart problems present from birth) that cannot be improved

Heart transplant procedure in pediatric EFE

Once a suitable donor heart is available, there is limited time to conduct the operation. Doctors follow strict protocol and check the patient for transplant suitability. If all goes well, then the operation is performed. 

Pre-transplant evaluation

Before proceeding with the transplant, doctors need to assess if the child is suitable to receive a transplant and undergo surgery. These are the main areas assessed: 

• Functional status: Doctors assess how well the child functions in daily life. This may include using the NYHA class (a scale from I to IV) to rate how severe the symptoms are, and checking exercise tolerance through walking and oxygen usage tests. If the child becomes tired or fatigued easily, it suggests a severe progression of the disease 
• Progression of heart failure: If the heart keeps getting worse after medication, a heart transplant is considered 
• Reversible conditions and other illnesses: Before transplant, it's crucial to rule out reversible causes of heart failure, such as valve disease or treatable infections, since correcting these might remove the need for a transplant. They also check for other major illnesses, because serious systemic disease can make a transplant unsafe or ineffective 
• Suitability for transplant and immune risks: Doctors will review overall factors such as age, weight, organ function, and lifestyle before a transplant

After a transplant, strong immunosuppressant medication is required to prevent rejection of the new organ. If the patient has autoantibodies or other immune system problems, there is a risk in prescribing immunosuppressants as they might not tolerate them. Therefore, blood tests are done beforehand to assess these risks. 

Surgical considerations

Operating on a paediatric patient’s heart is technically demanding. The native heart is markedly enlarged, with ventricles thickened by diffuse fibroelastic tissue. Careful dissection is crucial to avoid injury to adjacent areas. Implantation of the donor heart must then be performed with precision, particularly in infants and small children, where the chest cavity offers limited space. These complex operations are carefully carried out by highly specialised surgeons. Highly specialized surgeons conduct the transplant with care. 

Perioperative care

After the transplant, the patient is admitted to the paediatric intensive care unit. Here, doctors closely monitor heart function and other vitals. Doctors use advanced monitoring to check how well the heart and circulation are working. Close monitoring allows early detection of graft dysfunction, arrhythmias, or bleeding.

Medicines called inotropes are prescribed to help the new heart’s pumping strength. Therefore, infection prevention measures and monitoring of vital signs are crucial in this stage.⁵ 

Post-transplant care

This stage focuses on ensuring the survival of the transplanted heart. Immunosuppressants such as tacrolimus, mycophenolate mofetil, and corticosteroids are taken for the rest of the patient’s life. Regular check-ups with cardiologists are crucial to monitor ventricular function and graft health. Pediatric patients also require close attention to growth, nutrition, and developmental milestones, as chronic illness and medications can hinder normal development. 

Complications 

Graft rejection can occur even with immunosuppressive therapy. Coronary allograft vasculopathy is a progressive narrowing of the graft’s coronary arteries, often leading to late graft failure. Immunosuppression, while essential, predisposes children to recurrent and sometimes life-threatening infections. Another serious complication is post-transplant lymphoproliferative disorder (PTLD), a malignancy linked to Epstein–Barr virus and chronic immunosuppression.

Summary 

Endocardial Fibroelastosis (EFE) is a rare but devastating condition affecting the heart. It is characterized by diffuse thickening of the walls of the heart, leading to heart failure. While medical and surgical therapies provide temporary stabilisation, heart transplants remain the only definitive treatment for advanced disease. With advances in surgical techniques, postoperative care, and immunosuppression, survival and quality of life after transplantation continue to improve.